At present, this type of mixing is done with mixing machines having large diameter components, necessitating high-powered motors to obtain adequate flow of the mixture. Combination mixing-grinding machines are also used, which agitate the mixture but cause breaking and grinding of the solid particles of the mixture. This is not beneficial when mixing a liquid with a pulverulent product having grains of a required size.
Another problem with these machines lies in the feeding of the pulverulent product into the mixing chamber. Powder product tends to thicken, especially under conditions of high humidity, resulting in a mixture with variable proportions of powder and liquid.
These machines also have a tendency to incorporate air together with the pulverulent material, forming foam in the tanks and causing a very serious problem in industry.